The present invention relates to a resistance heater for a liquid system, to a liquid system comprising a resistance heater according to the invention; to a method for detecting the liquid level in a liquid system according to the invention, and to a method for detecting the temperature of a liquid in a liquid system according to the invention.
Liquid systems exposed to free ambient conditions are under some circumstances subject to temperatures below the solidification point of the liquids used. This leads to the necessity to integrate heating elements into the liquid systems which are activated as a function of the liquid temperatures and ambient temperatures.
For example, German Patent DE 102 22 946 discloses a plastic resistance heater in which two side-by-side contact rods are connected to one another by a plastic resistance material. The contact rods are completely sheathed by the plastic resistance material in the zones inside the fuel system. One disadvantage of this resistance heater is that no sensor elements are provided to support the operation of the resistance heater. If the heater is to operate autonomously, these must additionally be provided, so that additional installation space is required, resulting in increased costs in terms of materials, installation and logistics.